package com.pi4j.concurrent;

/*-
 * #%L
 * **********************************************************************
 * ORGANIZATION  :  Pi4J
 * PROJECT       :  Pi4J :: Java Library (Core)
 * FILENAME      :  SingleThreadGpioExecutorServiceFactory.java
 *
 * This file is part of the Pi4J project. More information about
 * this project can be found here:  https://pi4j.com/
 * **********************************************************************
 * %%
 * Copyright (C) 2012 - 2021 Pi4J
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * This {@link ExecutorServiceFactory} extends the {@link DefaultExecutorServiceFactory} but changes the GPIO event
 * executor to be single threaded
 */
public class SingleThreadGpioExecutorServiceFactory extends DefaultExecutorServiceFactory {

	private static class GpioEventExecutorServiceHolder {
		static final ExecutorService heldExecutor = Executors
				.newSingleThreadExecutor(getThreadFactory("pi4j-gpio-event-executor-%d"));
	}

	private static ExecutorService getInternalGpioExecutorService() {
		return GpioEventExecutorServiceHolder.heldExecutor;
	}

	private static class GpioEventExecutorServiceWrapperHolder {
		static final ExecutorService heldWrapper = new ShutdownDisabledExecutorWrapper(
				getInternalGpioExecutorService());

	}

	private static ExecutorService getGpioEventExecutorServiceWrapper() {
		return SingleThreadGpioExecutorServiceFactory.GpioEventExecutorServiceWrapperHolder.heldWrapper;
	}

	@Override
	public ExecutorService getGpioEventExecutorService() {
		// we return the protected wrapper to prevent any consumers from
		// being able to shutdown the scheduled executor service
		return getGpioEventExecutorServiceWrapper();
	}

	@Override
	public void shutdown() {
		shutdownExecutor(getInternalGpioExecutorService());
		super.shutdown();
	}
}
